Ankur Gupta, University of Colorado Boulder

Modern life relies on electricity and electrical devices, from cars and buses to phones and laptops, to the electrical systems in homes. Behind many of these devices is a type of energy storage device, the supercapacitor. My team of engineers is working on making these supercapacitors even better at storing energy by studying how they store energy at the nanoscale.

Supercapacitors, like batteries, are energy storage devices. They charge faster than batteries, often in a few seconds to a minute, but generally store less energy. They're used in devices that require storing or supplying a burst of energy over a short span of time. In your car and in elevators, they can help recover energy during braking to slow down. They help meet fluctuating energy demand in laptops and cameras, and they stabilize the energy loads in electrical grids.

Batteries operate via reactions in which chemical species give or take electrons. Supercapacitors, in contrast, do not rely on reactions and are kind of like a charge sponge. When you dip a sponge in water, it soaks up the water because the sponge is porous – it contains empty pores where water can be absorbed. The best supercapacitors soak up the most charge per unit of volume, meaning they have a high capacity for energy storage without taking up too much space.

In research published in the journal Proceedings of the National Academy of Sciences in May 2024, my student Filipe Henrique, collaborator Pawel Zuk and I describe how ions move in a network of nanopores, or tiny pores that are only nanometers wide. This research could one day improve the energy storage capabilities of supercapacitors.

All about the pores

Scientists can increase a material's capacitance, or ability to store charge, by making its surface porous at the nanoscale. A nanoporous material can have a surface area as high as 20,000 square meters (215,278 square feet) – the equivalent of about four football fields – in just 10 grams (one-third of an ounce) of weight.

Over the past 20 years, researchers have studied how to control this porous structure and the flow of ions, which are tiny charged particles, through the material. Understanding the flow of ions can help researchers control the rate at which a supercapacitor charges and releases energy.

But researchers still don't know exactly how ions flow into and out of porous materials.

Each pore in a sheet of porous materials is a small hole filled with both positive and negative ions. The pore's opening connects to a reservoir of positive and negative ions. These ions come from an electrolyte, a conductive fluid.

For instance, if you put salt in water, each salt molecule separates into a positively charged sodium ion and a negatively charged chloride ion.

When the surface of the pore is charged, ions flow from the reservoir into the pore or vice versa. If the surface is positively charged, negative ions flow into the pore from the reservoir, and positively charged ions leave the pore as they're repelled away. This flow forms capacitors, which hold the charge in place and store energy. When the surface charge is discharged, the ions flow in the reverse direction and the energy is released.

Now, imagine a pore divides into two different branched pores. How do the ions flow from the main pore to these branches?

Think of the ions as cars and pores as roads. Traffic flow on one single road is straightforward. But at an intersection, you need rules to prevent an accident or traffic jam, so we have traffic lights and roundabouts. However, scientists don't totally understand the rules that ions flowing through a junction follow. Figuring out these rules could help researchers understand how a supercapacitor will charge.

Modifying a law of physics

Engineers generally use a set of physics laws called “Kirchoff's laws” to determine the distribution of electrical current across a junction. However, Kirchhoff's circuit laws were derived for electron transport, not ion transport.

Electrons only move when there's an electric field, but ions can move without an electric field, through diffusion. In the same way a pinch of salt slowly dissolves throughout a glass of water, ions move from more concentrated areas to less concentrated areas.

Kirchhoff's laws are like accounting principles for circuit junctions. The first law says that the current entering a junction must equal the current leaving it. The second law states that voltage, the pressure pushing electrons through the current, can't abruptly change across a junction. Otherwise, it would create an extra current and disrupt the balance.

Since ions also move by diffusion and not only by the use of an electric field, my team modified Kirchhoff's laws to fit ionic currents. We replaced voltage, V, with an electrochemical voltage, φ, which combines voltage and diffusion. This modification allowed us to analyze networks of pores, which was previously impossible.

We used the modified Kirchoff's law to simulate and predict how ions flow through a large network of nanopores.

The road ahead

Our study found that splitting current from a pore into junctions can slow down how fast charged ions flow into the material. But that depends on where the split is. And how these pores are arranged throughout the materials affects the charging speed, too.

This research opens new doors to understanding the materials in supercapacitors and developing better ones.

For example, our model can help scientists simulate different pore networks to see which best matches their experimental data and optimize the materials they use in supercapacitors.

While our work focused on simple networks, researchers could apply this approach to much larger and more complex networks to better understand how a material's porous structure affects its performance.

In the future, supercapacitors may be made out of biodegradable materials, power flexible wearable devices, and may be customizable through 3D printing. Understanding ion flow is a key step toward improving supercapacitors for faster electronics.

Ankur Gupta, Assistant Professor of Chemical and Biological Engineering, University of Colorado Boulder

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Adrienne Mayor, Stanford University

When a wild orangutan in Sumatra recently suffered a facial wound, apparently after fighting with another male, he did something that caught the attention of the scientists observing him.

The animal chewed the leaves of a liana vine – a plant not normally eaten by apes. Over several days, the orangutan carefully applied the juice to its wound, then covered it with a paste of chewed-up liana. The wound healed with only a faint scar. The tropical plant he selected has antibacterial and antioxidant properties and is known to alleviate pain, fever, bleeding and inflammation.

The striking story was picked up by media worldwide. In interviews and in their research paper, the scientists stated that this is “the first systematically documented case of active wound treatment by a wild animal” with a biologically active plant. The discovery will “provide new insights into the origins of human wound care.”

To me, the behavior of the orangutan sounded familiar. As a historian of ancient science who investigates what Greeks and Romans knew about plants and animals, I was reminded of similar cases reported by Aristotle, Pliny the Elder, Aelian and other naturalists from antiquity. A remarkable body of accounts from ancient to medieval times describes self-medication by many different animals. The animals used plants to treat illness, repel parasites, neutralize poisons and heal wounds.

The term zoopharmacognosy – “animal medicine knowledge” – was invented in 1987. But as the Roman natural historian Pliny pointed out 2,000 years ago, many animals have made medical discoveries useful for humans. Indeed, a large number of medicinal plants used in modern drugs were first discovered by Indigenous peoples and past cultures who observed animals employing plants and emulated them.

What you can learn by watching animals

Some of the earliest written examples of animal self-medication appear in Aristotle's “History of Animals” from the fourth century BCE, such as the well-known habit of dogs to eat grass when ill, probably for purging and deworming.

Aristotle also noted that after hibernation, bears seek wild garlic as their first food. It is rich in vitamin C, iron and magnesium, healthful nutrients after a long winter's nap. The Latin name reflects this folk belief: Allium ursinum translates to “bear lily,” and the common name in many other languages refers to bears.

Pliny explained how the use of dittany, also known as wild oregano, to treat arrow wounds arose from watching wounded stags grazing on the herb. Aristotle and Dioscorides credited wild goats with the discovery. Vergil, Cicero, Plutarch, Solinus, Celsus and Galen claimed that dittany has the ability to expel an arrowhead and close the wound. Among dittany's many known phytochemical properties are antiseptic, anti-inflammatory and coagulating effects.

According to Pliny, deer also knew an antidote for toxic plants: wild artichokes. The leaves relieve nausea and stomach cramps and protect the liver. To cure themselves of spider bites, Pliny wrote, deer ate crabs washed up on the beach, and sick goats did the same. Notably, crab shells contain chitosan, which boosts the immune system.

When elephants accidentally swallowed chameleons hidden on green foliage, they ate olive leaves, a natural antibiotic to combat salmonella harbored by lizards. Pliny said ravens eat chameleons, but then ingest bay leaves to counter the lizards' toxicity. Antibacterial bay leaves relieve diarrhea and gastrointestinal distress. Pliny noted that blackbirds, partridges, jays and pigeons also eat bay leaves for digestive problems.

Weasels were said to roll in the evergreen plant rue to counter wounds and snakebites. Fresh rue is toxic. Its medical value is unclear, but the dried plant is included in many traditional folk medicines. Swallows collect another toxic plant, celandine, to make a poultice for their chicks' eyes. Snakes emerging from hibernation rub their eyes on fennel. Fennel bulbs contain compounds that promote tissue repair and immunity.

According to the naturalist Aelian, who lived in the third century BCE, the Egyptians traced much of their medical knowledge to the wisdom of animals. Aelian described elephants treating spear wounds with olive flowers and oil. He also mentioned storks, partridges and turtledoves crushing oregano leaves and applying the paste to wounds.

The study of animals' remedies continued in the Middle Ages. An example from the 12th-century English compendium of animal lore, the Aberdeen Bestiary, tells of bears coating sores with mullein. Folk medicine prescribes this flowering plant to soothe pain and heal burns and wounds, thanks to its anti-inflammatory chemicals.

Ibn al-Durayhim's 14th-century manuscript “The Usefulness of Animals” reported that swallows healed nestlings' eyes with turmeric, another anti-inflammatory. He also noted that wild goats chew and apply sphagnum moss to wounds, just as the Sumatran orangutan did with liana. Sphagnum moss dressings neutralize bacteria and combat infection.

Nature's pharmacopoeia

Of course, these premodern observations were folk knowledge, not formal science. But the stories reveal long-term observation and imitation of diverse animal species self-doctoring with bioactive plants. Just as traditional Indigenous ethnobotany is leading to lifesaving drugs today, scientific testing of the ancient and medieval claims could lead to discoveries of new therapeutic plants.

Animal self-medication has become a rapidly growing scientific discipline. Observers report observations of animals, from birds and rats to porcupines and chimpanzees, deliberately employing an impressive repertoire of medicinal substances. One surprising observation is that finches and sparrows collect cigarette butts. The nicotine kills mites in bird nests. Some veterinarians even allow ailing dogs, horses and other domestic animals to choose their own prescriptions by sniffing various botanical compounds.

Mysteries remain. No one knows how animals sense which plants cure sickness, heal wounds, repel parasites or otherwise promote health. Are they intentionally responding to particular health crises? And how is their knowledge transmitted? What we do know is that we humans have been learning healing secrets by watching animals self-medicate for millennia.

Adrienne Mayor, Research Scholar, Classics and History and Philosophy of Science, Stanford University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Albert Fox Cahn, New York University

The Philadelphia Inquirer recently investigated Philadelphia's use of what it described as a “little-scrutinized, 7,000-camera system that is exposing residents across the city to heightened surveillance with few rules or safeguards against abuse.” The article detailed how Philadelphia narcotics cops not only allegedly failed to disclose their use of video surveillance in arrest reports or to prosecutors, but also that the video footage at times proved officers were lying when they testified.

The Conversation U.S. talked to Albert Fox Cahn, founder and executive director of the nonprofit Surveillance Technology Oversight Project and a practitioner-in-residence at NYU School of Law, about what these new video systems can do and the privacy and other issues they raise.

What can these cameras do?

The closed-circuit television, or CCTV, cameras most Americans pass each day may look interchangeable, but a lot has changed behind the lens in recent years. As video surveillance cameras have become cheaper and more ubiquitous, they have also grown more powerful – featuring increasingly high-definition images and the ability to pan, tilt and zoom. But the most significant change to cameras like those used in Philadelphia is the networks that police departments set up to aggregate these countless images of city residents' daily lives.

A variety of AI tools can also harvest this data in new ways that some may find alarming.

Automated license plate reader software can both track drivers across the city in real time and create a long-term log of their cars' movements. Want to know where a driver is now or was parked two years ago? Just check the database.

And pedestrians are no less prone to surveillance. Facial recognition software can scan images to automatically identify individuals and track them across the city.

How widespread is this technology?

According to the Inquirer's investigation, Philadelphia's camera network grew at an astounding pace. In the past decade, the city has gone from 216 cameras to a network of more than 7,000 cameras operated by police and transportation officials.

But those are just the cameras that city officials directly control and can access in real time.

In addition, police routinely turn to the images captured by private surveillance cameras. This includes everything from multimillion-dollar, internet-enabled camera systems at large stores, offices and universities to the individual cameras that homeowners or small-business owners screw into their door frames or exteriors. The public simply has no idea how many of these private cameras are in operation or how often their data is requested.

How is this different from traditional police video surveillance?

Traditional cameras offered a narrow, grainy perspective on a single fixed place. These systems not only collected much less data than contemporary cameras, but they also retained far less.

A single CCTV camera at a bank might help police identify a suspect in a robbery, but it poses no privacy threat beyond that. It is confined to a small space where privacy concerns are minimal and security concerns are high. But mass camera deployments create a fundamentally different model, collecting far more information on all of us and creating far greater potential for misuse.

Police have attempted these techniques for decades, but the technology simply wasn't up to the task. When the City of London Police deployed its so-called “ring of steel” security system in the 1990s, fewer than two dozen cameras tried to track the cars entering a tiny portion of the British capital, surveilling roughly a square kilometer of the city's financial core. Officers manually jotted down vehicle plate numbers and surveilled drivers' profile photos.

The labor-intensive exercise was impossible to scale.

To deploy such a system across an entire city would likely have taken every police officer in the city and then some. Through automation, technology enables this mass surveillance by reducing the marginal cost of tracking, allowing police to expand monitoring far more broadly than would have been financially or pragmatically possible before.

What privacy concerns does it raise?

A single camera can capture our image; a citywide camera system can reconstruct our lives. Networked camera systems like those in Philadelphia, when combined with smartphones and other internet-enabled devices, allow officers to reconstruct an individual's movements for days or weeks at a time, all without any court oversight.

While it would take a warrant to install a GPS tracker on a resident's car, police can recreate GPS-like location tracking without a warrant, all thanks to mass camera systems. And facial recognition in municipal cameras threatens the First Amendment, which protects freedom of speech, religion and peaceful assembly. The police are armed with a way to track nearly every person at a political protest, abortion clinic or house of worship. Such surveillance melts away the anonymity that is indispensable to an open society.

Are there other risks or unintended consequences?

I believe giving thousands of city employees the keys to a small surveillance state is a recipe for disaster.

The Philadelphia Inquirer found that the city has policies that forbid zooming in on residents for amusement, spying on someone by zooming in through their window, or blatant racial profiling. But what it didn't find was evidence that these safeguards were being enforced.

When thousands of employees can spy on their neighbors, romantic partners and business rivals on a whim, it raises the question: Who watches the watchers?

At least for now, the grim answer appears to be no one.

Albert Fox Cahn, Practitioner-in-Residence, Information Law Institute, New York University

This article is republished from The Conversation under a Creative Commons license. Read the original article.